Optical photonic diode realization through spatial self-phase modulation using Mn3O4 nanoparticles

Abstract

The growing demand for efficient nonlinear optical (NLO) materials for photonic devices such as isolators, switches, and telecommunication components necessitates the exploration of new nanostructured systems. Transition metal oxides like Mn₃O₄, with strong electronic interactions and thermal responses, remain relatively underexplored for their NLO behavior. In this work, Mn₃O₄ nanoparticles synthesized via ultrasonication-assisted precipitation were investigated using spatial self-phase modulation (SSPM) with a 532 nm CW DPSS laser. Structural and morphological characteristics were confirmed by XRD and TEM analyses. Nonlinear optical parameters, including the nonlinear refractive index (n₂) and thermo-optic coefficient $\frac{\text{dn}}{dT}$ , were determined from the variation of SSPM patterns with laser intensity. Furthermore, a photonic diode based on a cascaded Mn₃O₄/TiO₂ hybrid structure was demonstrated, enabling nonreciprocal light propagation through unidirectional SSPM excitation. These findings highlight Mn₃O₄ nanoparticles as promising candidates for NLO applications, while the proposed hybrid photonic diode offers potential in integrated optics, optical switching, and telecommunication technologies.